Dissecting Reactions of Nonlinear Precursor Peptide Processing of the Class Ⅲ Lanthipeptide Curvopeptin

摘要

Lanthipeptides are ribosomally synthesized peptides which undergo extensive post-translational modifications. In addition to novel structural features and bioactivities, the in vitro study on the biosynthesis of the class Ⅲ lanthipeptide labyrinthopeptin revealed a unique C- to N-terminal directionality of biosynthetic processing. The recently described class Ⅲ lanthipeptide curvopeptin allowed investigating the directionality aspect in much greater detail: Structural characterization of nine curvopeptin biosynthesis intermediates by high-resolution mass spectrometry combined with a deuterium-labeling approach enabled for the first time building a comprehensive biosynthesis model featuring all three post-translational modification reactions: phosphorylation, elimination, and cyclization. These results point to a nonlinear processing scheme with a predominant C → N-terminal directionality. Our data give important mechanistic insights into the concerted processing and directionality of the multifunctional class Ⅲ modifying enzymes. The data are of significance in the light of obtaining a mechanistic understanding of the post-translational biosynthesis machinery of the growing variety of ribosomally synthesized and post-translationaUy modified peptides.